PoE 100base hack

I have wanted to add another WiFi access point to my shed. I had a cheap Chinese one that had a 100Mb port so I could use a simple injector system with the unused pairs.

Layout of system

I purchased a cheap PoE injector/splitter off eBay and attached a 5v PSU as he injector. Unfortunately it kept power cycling as the volt drop from the length of Ethernet cable was too much.

The access point has accessible pins on the RJ45 jack and the transformer also has accessible centre taps on the 2 data lines for Power over data lines .

Ethernet isolation transformer

To make this self contained I would have to get the 12ish volt and put it into the onboard step down regulators. Unfortunately I could not find any information on these Za7J1 5pin beasts to find out the maximum voltage input they can handle, so an external regulator it is.

NEXX WT3020 mini wireless router flashed with Open WRT

This next part may hurt some people. Someone had given me a locked Fetch TV box with a 1TB HDD. I couldn’t find anything online on how to unlock it so I grabbed the HDD out and repurposed the PCB for this project. There are multiple power rails derived from the 12v input on the board along with USB ports hooked up to the 5v rail, which I plan on using to power the access point.

The PCB was too bulky so I simply cut the power supply section of the board off with the USB ports. The USB ports are protected with a over-current protection IC MP6212, which I shorted the enable to 5V (pins 3-4) to supply 5v to the USB jack.

USB output protection IC

I plugged it all together with a 12v adaptor at the injector end and it worked well with a nice regulated 5v being supplied to the shed access point.

By David Dobson

I try not to let my age dictate how old I act

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